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PREPRINT NO. 550

CREATIVE ASPECTS OF LIVE-PERFO_NCEELECTRONIC MUSIC TECHNOLOGY

byGordon MummaCunningham Dance FoundationNew York, New York

PR ES EN TE D A T TH E3 3rd CONVENT IONOCT. 16 - OCT. 19, 1967

, _ AN AUDIO ENGINEERING SOCIETY PREPRINT

This preprint has been reproduced from the author's advance manuscript, without editing or corrections. ForConventionPrice ...... $.25 this reason there may be changes should this paper beByMail to Members.... $.50 published in the Audio Engineering Society Journal.ByMail to Non-Members . $.85 Addit ional preprints may be obtained by sending re-

quest and remittance to the Audio Engineering SocietyRoom428, 60 East42nd Street, New York, N.Y. 10017.


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Gordon _MmmaCunningham Dance FoundationNew York, New York

CRF_ATIVE ASPECTS OF LIVE-PF_RFOR_NCE ELECTRONIC MUSICTECItNOLOGYI am a composer and performing musician by pro-fession, with considerable experience in acoustics and

electronics, particularly solid-state technology. 1_work in electronic music began in 1957, with the makingof film soundtracks and electronic music for theatre,and within a year I had established an electronic musicstudio.

Since that time my work with electronic musichas evolved from its primacy as a magnetic tape mediumto an almost complete preoccupation with live-perfo_lanceelectronic means. I like being a performing musician, Ilike the sound control possible with electronic technology,and i like to compose electronic music which I can performlive for paying audiences.

_ o_m electronic music equipment is designedas part of the process of composing my music. I am reallylike the composer who builds his own instruments, thoughmost of my "instruments" are inseparable from the compo-sitions themselves.

1_ "end-product" is more than a package ofelectronic hardware, it is a performance of music. Thus,on occasion my technical concerns may be differently orien-ted than those of the usual electronic engineer. Nonethe-less, we are concerned with common ground: the applicationsof electronic technology to music.


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AES / Creative Aspects / page 2

The four mus'ical compositions which I willdiscuss have at least two aspects in common: conventionalmusical instruments are used as sound sources for elec-tronic sound processing, and they are all live-performanceworks. The first three compositions are included to in-dicate the diversity of configuration possible with veryfew basic electronic functions. These functions are am-plitude modulation, frequency modulation, and frequencyfiltering. The fourth composition is given in more detailbecause of its greater complexity, and because it ispossible to hear illustrative examples from a recentrecording of the work.

Though I may describe my use of certain elec-tronic procedures because they result in certain sounds,these procedures were not ahvays chosen on a cause andeffect basis. Sometimes I am after a certain kind ofsound modification and I work on various circuits untilI have achieved that modification. Other times I may havebeen casually experimentin_ with different configurationsof circuits and I chance upon some novel sound effect whichbecomes the germinating idea for a piece of music.

I am concerned with "system-concepts": configurationswhich include sound sources, electronic modification circuitry,control or logic circuitry, playback apparatus (power am-plifiers, loudspealoors, and the auditorium), and even socialconditions beyond the confines of technology. I suggestthat the most important creative aspect of live-performanceelectronic music technology is not this or that circuitinnovation, but rather the total configuration itself.

Technically, and in conception, tile first ofthese works is the most elementary. Aledium Size Mograph1963 is an eight minute composition for piano with two


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The second piece is called Hornpipe (1967). Thisis a composition for solo French IIorn. The instrument hasbeen modified and contains a special microphone. A fewfeet behind tile performer is a series of vertical pipes,containing their own microphones and resonant at differentfrequencies. Further behind is the loudspeaker from whichthe music is heard. All of the microphones are appliedto tlle sound modifying circuitry, but at different pointsin the configuration.

Tile acoustical feedback loop which exists betweenthe French t_rn, the resonant pipes, and the loudspeaker,is part of an electronic feedback system which employsamplitude gated frequency translation.

As the performance begins the system is balanced.Sound is produced only when something in the acoustic-electronic feedback-loop system is unbalanced. The initialsounds produced by the French Hornist unbalance parts ofthe system, some of which rebalance themselves and unbalanceother parts of the system. The performer's task is tobalance and unbalance the right thing at the right time,in the proper sequence.

The third work I want to cite is titled Diastasis,as in Beer (1966). It is composed for two electric guitars.As the title implies, the two guitars in performance areinterdependent but separating in a special Amy.

Briefly, the pitch (or frequency) of each guitaris determined by the amplitude envelope of tile other guitar.The frequency spectrum is shifting continuously rather thandiscretely (as would ordinarily occur on a fretted instrument)._vo special frequency modulators accomplish this task, andthe process is complicated because the amplitude-envelope


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Tile title of the piece is 5_SA. I wanted apredominant character of the music to--]_ of sustainedsounds at one level interrupted by sounds of greatlycontrasting loudness. I had already given up the ideaof a composition on magnetic tape, because the kind ofdynamic range I wanted simply isn't possible with tape.

My concept for _SA included the use of ani_larmonic frequency specr%_r-u_with extremes of sounddensity. To achieve this, as well as to control aspectsof the spatial perception of the audience, and stillmaintain clarity in the musical continuity, I deployinharmonically related portions of the sound throughdifferent loudspeakers in the auditorium. Thus, thefinal "processing" of tile sound is the mixing of in-harmonically related, spatially deployed sounds in eachlistener's two ears. In contrast to Diastasis_ as inBeer, the pitch changes of _SA are discrete rather thanco----_inuous.

David Tudor plays the Bandoneon, an accordion-like Argentine instrument, and with it can produce ex-tremely long, sustained sounds over a wide frequency anddynmnic range. The Bandoneon became my sound-source for

, and the technical problems included, besides ex-lng the dynamic rm_ge, frequency-translation andequalization to obtain the desired timbres, and a con-figuration of logic circuitry to control the continuityof the music.Extending the dynamic range was the most com-plicated problem, because a wide range of sound envelopecontrols had to be included in the same circuitry. These

functions are completely automatic in _SA, and are achievedwith four VOLTAGE CONTROLLED ATTENUATORS (VCA) developed


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are usually heard from behind the audience. Though notindicated in this diagram, voltage amplification atvarious levels is included in the circuitry wherevernecessary.

A closer view of the interrelated sound modifi-cation functions can be seen within one of the systemblocl_. The functions of one of the modifiers are out-lined in Figure 2.

The SPECTRUMTRANSFER is a frequency shifterwith equalization. The amount of frequency shift isdetermined either by variable internal control signalsor by an external signal derived from the Bandoneonitself. The source and nature of the control signalis determined by the FM LOGIC.

The MULTIPLIER translates portions of theprogram spectrum by whole integers and equalizes theproduct.

The PRODUCTVALVE is a combination amplitudeand phase modulator, the product of which contains theoutput of the SPECTRUM TRANSFER plus a new spectrumderived by amplitude gating the SPECTRUM TRANSFER out-put with part of the MULTIPLIER output.

The MODIFIER ROUTE-GATE LOGIC is an adder withthree inputs, two outputs, and a control signal. Thiscontrol signal comes from an external ROUTE-GATE LOGICmodule and determines (1) the proportions of the threeinputs (from the SPECTRUM TRANSFER, the MULTIPLIER, andthe PRODUCTVALVE), and (2) the balance of the two out-puts (to the FORWENT MODULATOR and the outrigger modifierchannel).


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control signals to frequency-sensitive thermal-delaycircuitry. The wide dynamic range of the VGA is dueto special bias procedures.All of the control signals for these soundmodification functions are derived from the Bandoneon

itself. Some are frequency (or phase) modulated, someare amplitude modulated, and in the VCA module some ofthe bias is derived from integration of control andprogram signal sums. Because the control signals areautomatically derived from the sound materials themselves,I call the process, and the music, "cybersonic".The LOGIC modules have two basic functions.

The FM LOGIC controls the operation of the SPECTRUM TRANS-FERS, determining the amount of program-signal frequency-shift by control signals derived from the outrigger VCAs.The ROUTE-GATE LOGIC modules determine aspects of thesound modification and, in conjunction with the actionsof the Bandoneon player, establish the musical continuity.If these logic modules are operated in their

fully automatic modes the most extreme performance situa-tion for _SA is possible: a duo between the Bandoneonistand the e_e'c'_ronic circuitry. Most often they are operatedsemi-automatically, with a second human performer makingdecisions and overriding parts of the internal logic.Usually this second performer is myself, the composer.Ail of the compositions I have cited are my own.During the past decade a substantial repertoire of live-performance electronic music has been made by other com-posers, in the United States, in Europe, and in Japan.The diversity of this repertoire is already sufficient to

support several performinE ensembles.


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_IAoT_ERt tMOD'F'ERI;'i ."o.,r,_er"left D I ROUTE-GATE LOGIC

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Bondoneon I FM LOGIC I primaryf j 4.0 " i I"I MODIFIER _-_-- .... "1 !I I

right D IROUTE-GATE LOGIC II_ -_"_1 I_D'F'_t__ "'_'_'_"!

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Figure I.


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